Novel Ester Compounds, Method for the Production Thereof and Use Thereof

ABSTRACT

The invention relates to ester compounds of the general formula (I) 
     
       
         
         
             
             
         
       
     
     to a process for preparation thereof and to the use thereof. These ester compounds may contain a mixture of at least two compounds of the general formula (I).

PRIORITY CLAIM

This application is a divisional of co-pending U.S. application Ser. No.16/493,830, which issued as U.S. Pat. No. 10,829,436, on Nov. 10, 2020,and which is a 35 U.S.C. 371 National Stage application ofPCT/EP2018/000197, filed Apr. 11, 2018 and claiming priority to GermanApplication Nos. DE 10 2017 003 647.0, filed on Apr. 13, 2017, DE 102018 002 891.8, filed on Apr. 10, 2018. The entire contents of theabove-mentioned patent applications are incorporated herein by referenceas part of the disclosure of this U.S. application.

BACKGROUND

The invention relates to novel ester compounds of the general formula(I)

to a process for preparation thereof and to the use thereof. These estercompounds may contain a mixture of at least two compounds of the generalformula (I).

Ester compounds have been used ever more frequently in lubricantformulations in the last few years. Since the ester units in the estercompounds in natural oils and also in synthetic ester oils are prone tohydrolysis, there is a great need for ester compounds that meet the highdemands for use in lubricants. In the case of the known ester compounds,when the lubricant is used in the presence of water, the ester ishydrolyzed to the fatty acid and the alcohol. This reaction can becatalyzed, for example, by acids or bases or by copper. This results inthe destruction of the molecules, as a result of which the lubricantslose their lubricating effect.

Furthermore, conventional lubricants, for example based on nativeesters, are unsuitable for high-temperature applications since they canbe destroyed at high temperatures by oxidation and/or thermaldecomposition processes and by polymerization, and hence theirlubricating properties and effects are greatly restricted. Indecomposition reactions, the lubricant is cleaved to give volatilecomponents of low molecular weight. The evaporating of these volatilecomponents leads to unwanted changes in viscosity and loss of oil, andto excess vapor formation. This likewise results in a loss of lubricity.The polymerization also causes the lubricants to lose their lubricityowing to the formation of insoluble polymerization products. Thissoiling has to be removed, which increases maintenance operations.Furthermore, chemical wastes are produced, which have to be disposed ofin a complex manner. Owing to the increased cleaning and maintenancework, there is an increase in the shutdown times of the devices to belubricated. Overall, the use of unsuitable lubricants inhigh-temperature applications leads to higher costs since the machineryis soiled and there is a high demand for lubricants. Furthermore, thereis a drop in product quality.

In order to meet the various demands, lubricants must have, among otherqualities, high stability, low coefficients of friction and high wearresistances. High temperatures often occur in the case of use in chains,ball bearings and slide bearings, in motor vehicle technology, inconveying technology, in mechanical engineering, in office technologyand industrial plants and machinery, but also in the fields of domesticappliances and consumer electronics. High processing temperatures oftenoccur, for example, in food processing, as in the case of cooking,baking, boiling, roasting, braising, sterilizing, frying and steaming.Various equipment is used in these operations. Lubrication of thisequipment requires high-temperature-resistant lubricants.

Particular demands are made on the base oils for lubrication ofequipment for the processing of foods in relation to environmentalcompatibility and toxicity. In principle, a food-compatible lubricant H1should be suitable when the lubricant can come into indirect or directcontact with foods, semi-luxury goods and foodstuffs. The preferredfields of use in the food industry include chains in baking ovens andother high-temperature applications, and also transport gears,especially trolleys and bearings thereof.

These lubricants are subject to legal requirements, such ascertification under NSF/H1 or NSF/H2.

In the case of applications of lubricants in the marine sector that areusually below the waterline, there is the risk of contamination of themarine or water environment as a result of escape of lubricants. Eventhough attempts are made to seal the water side as best possible inthese applications, lubricant losses are an everyday occurrence.

According to a source at the United States Environmental ProtectionAgency in 2011, different ship constructions lose from less than oneliter of lubricant up to 20 liters per day per ship. Goodbiodegradability of the lubricant here is a prerequisite for highenvironmental compatibility of the lubricants. Generally, suchapplications are regulated by legal requirements or standards, forexample VGP, Eco-Label or OSPAR.

However, the lubricants known to date are unable to meet all theserequirements.

There have already been proposals to use what are called estolidecompounds in lubricants. These ester compounds, which are generallybased on vegetable oils, are synthesized according to S. C. Cermak etal., Industrial Crops and Products 2013, 46, 386-392. According to thisliterature and patent specification EP 1 051 465 B1, this affordscompounds of the general structure Lit-1 shown in FIG. 1, where x and yare equal to or greater than 1, x+y is 10, n is equal to or greater than1, R is CHR₁R₂, R₁ and R₂ are each independently selected from hydrogenand saturated or unsaturated, branched or unbranched, substituted orunsubstituted and C1 to C36 hydrocarbons, R₃ is a structural fragmentresulting from oleic acid, stearic acid or other fatty acids, and thepreferred position of the secondary ester branch is at the 9 or 10position (corresponding to x=5 or 6 and y=5 or 4).

These estolide compounds of the Lit-1 type are prepared according to theabove-cited literature by addition of a fatty acid onto the C═C doublebond of the next fatty acid, so as to obtain corresponding dimers (n=0)and additionally also tri-, tetra-, penta- and hexamers (n=1, 2, 3, 4).However, the structure shown, from the perspective of scientificrepresentation of a repeat unit, cannot be correct since the linkage ofthe repeat unit is not apparent therefrom. Disadvantages of this processare the low selectivity (which leads correspondingly not to a definedproduct compound but to a mixture of dimer and oligomer mixtures), theharsh reaction conditions, the low yield and the complex separation ofdimer/oligomer mixtures. The two concluding steps are then thehydrogenation of the remaining C═C double bond and the esterification ofthe remaining carboxylic acid group, where the alcohol component used ispreferably 2-ethylhexan-1-ol.

SUMMARY OF THE DISCLOSURE

It is therefore an object of the present invention to provide novelester compounds which meet the abovementioned demands for use inlubricants and which is producible from simple and readily available,preferably renewable, raw materials as starting materials by asustainable and environmentally friendly route. Furthermore, thesynthesis method is to have a high selectivity, a high yield is to beachieved and simple workup is to be possible.

This object is achieved by the provision of novel ester compounds andsuitable synthesis methods for preparation thereof.

The ester compounds of the invention have the general formula (I) shownbelow and are a mixture of at least two compounds of the general formula(I)

in which

-   -   the A radical is selected from the group consisting of CH₂,        CH₂CH₂, cis-CH═CH and/or trans-CH═CH,    -   n is 0 or 1 to 20,    -   m is 0 or 1 to 20,    -   the R¹ radical is selected from the group consisting of        hydrogen, branched or unbranched C₁- to C₆₀-alkyl radicals,        branched or unbranched C₂- to C₆₀-alkenyl radicals, C₇- to        C₆₀-arylalkyl radicals, C₁- to C₆₀-heteroarylalkyl radicals, C₆-        to C₆₀-aryl radicals, and/or cyclically saturated or unsaturated        C₅- to C₆₀-alkyl radicals, where these are unsubstituted or        mono- or polysubstituted by at least one substituent selected        from the group of OH, R⁴, R⁵, O-acetyl,    -   the R² radical is selected from the group consisting of H,        branched or unbranched C₂- to C₆₀-alkyl radicals, C₂- to        C₆₀-heteroalkyl radicals, C₇- to C₆₀- arylalkyl radicals, C₆- to        C₆₀-heteroarylalkyl radicals, C₆- to C₆₀-aryl radicals, and/or        cyclically saturated or unsaturated C₅- to C₆₀-alkyl radicals,        where these are unsubstituted or mono- or polysubstituted by at        least one substituent selected from the group of OH, O—C(O)—R¹,        CH₂OH, CO₂H, CO₂R¹, R⁵, and additionally, in the case that m=1        to 20, also branched or unbranched C₂- to C₆₀-alkenyl radicals        or methyl, where this is unsubstituted or mono- or        polysubstituted by at least one substituent selected from the        group of OH, O—C(O)—R¹, CH₂OH, CO₂H, CO₂R¹, R⁵,    -   the R³ radical is selected from the group consisting of branched        or unbranched C₁- to C₆₀-alkyl radicals, branched or unbranched        C₂- to C₆₀-alkenyl radicals, C₇- to C₆₀-arylalkyl radicals        and/or C₆- to C₆₀-heteroarylalkyl radicals, where these are        unsubstituted or mono- or polysubstituted by at least one        substituent selected from the group of OH, CH₂OH, CH₂—R⁴,    -   the R⁴ radical has the following structure (II):

where the R², R³ and A radicals and the numbers m and n present thereinare defined as described above,

-   -   the R⁵ radical has the following structure (III):

-   -   where the R¹, R³ and A radicals and the numbers m and n present        therein are defined as described above.

In addition, mixtures containing at least two compounds having thegeneral structure (I) are also provided, where two of these compounds ineach case are regioisomers of one another. These pairs of regioisomersresult from the simultaneous introduction of the hydroxymethyl functionin, for example, the 9 and 10 position in the case of thehydroformylation of the double bond in the 9,10 position. Subsequently,proceeding from such a “regioisomer pair”, it is alternatively possibleto prepare mixtures, the different “m”. These compounds in turn, bycomparison, are no longer all regioisomers of one another.

By contrast with the known estolide compounds having the structure Lit-1shown in FIG. 1, the inventive compounds having the general structure(I) have an additional “methylene bridge” (methylene unit, —(CH₂)—)between the carbon of the fatty acid chain and the oxygen of the C—Osingle bond of the adjacent ester group. This “methylene bridge” opensup additional options with regard to changes in conformation of therespective molecules and can thus contribute to higher stericflexibility, combined with correspondingly advantageous productproperties. This also opens up the option of novel product properties bycomparison with other rigid lubricants, for example the estolidecompounds. By contrast with the estolide compounds which, according tothe description, is prepared by linkage of multiple unsaturated fattyacids as a result of uncontrolled addition of the carboxylic acid unitof an unsaturated fatty acid with the alkene unit of a furtherunsaturated fatty acids and correspondingly leads to mixtures ofcompounds of different chain length, the controlled preparation ofcompounds of a particular chain length is possible with the aid of theprocess of the invention, where these take the form of regioisomers.This selective synthesis of compounds of different chain length and thepresence thereof in isolated form enables later controlled “blending”,i.e. the mixing of compounds of different chain length tailored to thedesired individual use for achievement of the desired lubricantproperties. The individual representatives of the compounds of theinvention thus form a modular “building block system”, which can then beused in a controlled manner for specific lubricant applications.

DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram of the general structure of estolide compounds ofthe prior art.

FIG. 2 is a diagram of the structure of compounds using oleic acidderivatives (Ia) according to the present disclosure.

FIG. 3 is a diagram of the structure of compounds using oleic acidderivatives (Ib) according to the present disclosure.

FIG. 4 is a diagram of the structure of compounds using oleic acidderivatives (Ic) according to the present disclosure.

FIG. 5 is a diagram of the steps for synthesizing a hydroformylationfrom oleic acid according to one aspect of the present disclosure.

FIG. 6 is a diagram of synthesizing strategies proceeding from oleicacid with the incorporation of an ene reaction according to a furtheraspect of the present disclosure.

FIG. 7 is a diagram of compounds of the general structure (Ib) preparedfrom 1,6-hexanediol as a diol component.

FIG. 8 is a diagram of compounds of the general structure (Ic) preparedfrom n-hexanedicarboxylic acid as a dicarboxylic acid component.

FIG. 9 is a diagram of compounds of the general structure (Ic) preparedfrom dicarboxylic acid Pripol 1013 as a dicarboxylic acid component.

DETAILED DESCRIPTION

Particularly preferred representatives of the inventive compounds of thegeneral formula (I) include those compounds that can be preparedproceeding from the unsaturated fatty acids oleic acid, linoleic acid,linolenic acid, erucic acid, nervonic acid, gadoleic acid and otherω-n-fatty acids.

One illustrative compound type of these particularly preferredrepresentatives of the inventive compounds having the general structure(I) is that of the oleic acid-derived compounds of the general structure(Ia) that are illustrated in FIG. 2, where m′ is 1 to 5, n′ and n″ areeither 1 and 2 or 2 and 1, and R¹ and R² have definitions describedabove.

A further compound type of the particularly preferred representatives ofthe inventive compounds having the general structure (I) is that of theoleic acid-derived compounds having “diol bridges” of the generalstructure (Ib) that are shown in FIG. 3, where m′ is 0 to 5, n′ and n″are either 1 and 2 or 2 and 1, n″' is 0 to 10, R¹ and R² have thedefinitions described above and the R⁶ radical is selected from thegroup consisting of branched or unbranched C₁- to C₆₀-alkyl radicals andbranched or unbranched C₂- to C₆₀-alkenyl radicals. In the case thatm′=1 to 5, the R² radical is additionally selected from the groupconsisting of branched or unbranched C₂- to C₆₀-alkenyl radicals ormethyl radical, where this is unsubstituted or mono- or polysubstitutedby at least one substituent selected from the group of OH, O—C(O)—R¹,CH₂OH, CO₂H, CO₂R¹, R⁵.

An alternative further illustrative compound type of the particularlypreferred representatives of the inventive compounds having the generalstructure (I) is that of the compounds having “dicarboxylic acidbridges” of the general structure (Ic) that are shown in FIG. 4, wherem′ is 0 to 5, n′ and n″ are either 1 and 2 or 2 and 1, n′″ is 0 to 10,R¹ and R² have definitions described above and the R⁶ radical isselected from the group consisting of branched or unbranched C₁- toC₆₀-alkyl radicals and branched or unbranched C₂- to C₆₀-alkenylradicals. In the case that m′=1 to 5, the R² radical is additionallyselected from the group consisting of branched or unbranched C₂- toC₆₀-alkenyl radicals or methyl group, where this is unsubstituted ormono- or polysubstituted by at least one substituent selected from thegroup of OH, O—C(O)—R¹, CH₂OH, CO₂H, CO₂R¹, R⁵.

The novel inventive compounds of type (I) can be prepared in variousways, and two preferred embodiments are described below. These synthesesdiffer considerably from those preparation methods that lead to otherlubricant compounds, for example by comparison with the processes forpreparing the estolide compounds, by way of which the compounds of theinvention are typically unobtainable.

Both preferred embodiments of the synthesis of the inventive compoundsof type (I) proceed from unsaturated fatty acid as starting compound.More particularly, oleic acid, linoleic acid, linolenic acid, erucicacid and nervonic acid, gadoleic acid and other ω-n-fatty acids are usedhere. The use of renewable raw materials as starting compounds isadvantageous here from the perspective of economy and sustainability.

There are different embodiments for each of the two abovementionedpreferred synthesis strategies. More particularly, it is possible tovary the sequence of the reaction steps involved in any way.

The two abovementioned preferred synthesis strategies are described indetail hereinafter.

In the first preferred embodiment, the process of the invention proceedsfrom an unsaturated fatty acid which is first esterified, or thecorresponding ester is used directly. This esterified product is thensubjected to a hydroformylation reaction in the presence of molecularhydrogen (H₂) and carbon monoxide (CO) and, after subsequenthydrogenation, which is preferably effected in situ, the correspondingmethylol-substituted derivative is obtained. These steps forhydroformylation of unsaturated fatty acids and the subsequenthydrogenation thereof to give the corresponding methylol-substitutedderivative have been described many times in the literature, for examplein R. Lai, M. Naudet, E. Ucciani, Rev. Fr. Corps Gras 1966, 13, 737-745,R. Lai, M. Naudet, E. Ucciani, Rev. Fr. Corps Gras 1968, 15, 5-21, R.Lai, E. Ucciani, M. Naudet, Bull. Soc. Chim. Fr. 1969, 793-797, E. N.Frankel, J. Am. Oil Chem. Soc. 1971, 48, 248-253, E. N. Frankel, F. L.Thomas, J. Am. Oil Chem. Soc. 1972, 49, 10-14, J. P. Friedrich, G. R.List, V. E. Sohns, J. Am. Oil Chem. Soc. 1973, 50, 455-458, E. H. Pryde,J. Am. Oil Chem. Soc. 1984, 61, 419-425, E. H. Pryde, J. Am. Oil Chem.Soc. 1984, 61, 419-425 and E. Benetskiy, S. Lühr, M. Vilches-Herrera, D.Selent, H. Jiao, L. Domke, K. Dyballa, R. Franke, A. Börner, ACS Catal.2014, 4, 2130-2136.

Review articles on this topic that are additionally available to theperson skilled in the art include, for example, the contributions by E.H. Pryde, E. N. Frankel, J. C. Cowan, J. Am. Oil Chem. Soc. 1972, 49,451-456, E. N. Frankel, Ann. N.Y. Acad. Sci. 1973, 214, 79-93, J. W. E.Coenen, Fette, Seifen, Anstrichmittel 1975, 77, 461-467, E. N. Frankel,E. H. Pryde, J. Am. Oil Chem. Soc. 1977, 54, 873A-881A, E. H. Pryde, J.Am. Oil Chem. Soc. 1979, 56, 719A-725A.

The hydroxyl group of the resultant methylol-substituted derivative isthen esterified again, which can be effected directly with anon-hydroxyl-substituted fatty acid, for example, or with anotherlong-chain alkanecarboxylic acid having at least one hydroxyl group (orester thereof in a transesterification reaction). This long-chainalkanecarboxylic acid having at least one hydroxyl group is preferably along chain fatty acid which bears at least one hydroxymethyl group andcan be prepared, for example, in the manner outlined above. For theesterification of the hydroxyl group for preparation of the dimers oroligomers, it is possible to use either the respective acids directly oractivated acid derivatives, e.g. acid chlorides and anhydrides, or acidesters (for a transesterification reaction). It is also possible to usedicarboxylic acids, tricarboxylic acids and higher carboxylic acids orderivatives thereof.

In detail, the first preferred embodiment of the process of theinvention for preparing inventive ester compounds of the general formula(I) comprises the following steps:

-   -   (A) proceeding from an unsaturated fatty acid or an ester        derived therefrom having the general formula (IV)

-   -   where R¹, R³ and n are as defined above,    -   a hydroformylation is conducted to form compounds having the        general formula (V)

-   -   where R¹, R³, A and n are as defined above, and    -   (B) the compounds obtained having the general formula (V) are        subsequently converted by hydrogenation to the compounds having        the general formula (VI)

-   -   where R¹, R³, A and n are as defined above, and    -   (C) then an ester formation reaction is conducted using an acyl        donor having the formula (VII)

-   -   where R¹, R², R³, A and n and m are as defined above, giving the        inventive compounds of the general formula (I)

-   -   where R¹, R², R³, A and n and m are as defined above.        Optionally, there can subsequently be an exchange of the R¹        group by an esterification or transesterification reaction.        Likewise optionally, in the case of a free hydroxyl group in the        R² radical, further esterification thereof is possible.

This first preferred embodiment is additionally presented or illustratedhereinafter using the example of preparation of corresponding inventivecompounds proceeding from oleic acid as an illustrative representativeof an unsaturated fatty acid as starting compound. This synthesis routeis additionally summarized in the form of a diagram in FIG. 5.

Proceeding from oleic acid 1 as a starting compound readily obtainablefrom a renewable raw material, there is firstly an esterificationreaction, wherein, in the illustrative example, 2-ethylhexan-1-ol isused as a readily available bulk chemical obtainable in large volumes(FIG. 5). For the esterification, there is generally a broad spectrum ofmethods available to the person skilled in the art, one attractivesynthesis option being catalytic methods using acids or biocatalysts,preferably a lipase.

The ester 2 obtained in the esterification reaction is subsequentlysubjected to a hydroformylation reaction, which gives rise to thecompound 3 substituted by a CH(═O)— radical in the 9 position (in amixture with the regioisomer substituted by a CH(═O)— radical in the 10position). The subsequent hydrogenation of the carbonyl group in 3 thenaffords the 9-methylol-substituted oleic ester 4 (in a mixture with the10-methylol-substituted regioisomer), which is subsequently converted tothe desired target compounds 5 by acylating the hydroxyl group.

The reaction steps of hydroformylation and hydrogenation can be combinedin such a way that, after the hydroformylation, the subsequenthydrogenation of the aldehyde group to give the methylol-substitutedderivative 4 is effected directly in situ. The hydroxymethyl group(methylol group) formed in the hydroformylation may, owing to thetypically low or not very pronounced regioselectivity of thehydroformylation reaction, be either in the 9 or 10 position and maytypically contain a mixture of the two isomers. For reasons of clarity,FIG. 5 shows only the 9-substituted isomer in the diagram. In theproducts of type 5 formed, compounds with m′=0 or 1 to 5 areparticularly preferred.

Alternatively, the target compounds can also be prepared by way of asecond, preferred embodiment by a route described hereinafter. In thiscase, an unsaturated fatty acid is first reacted with formaldehyde (or aformaldehyde derivative, for example paraformaldehyde) in an enereaction, optionally a subsequent reduction of the resulting C═C bond(for example via a heterogeneously catalyzed hydrogenation), andfollowed by a subsequent esterification. Here too, the sequence can bevaried and can first be commenced, for example, with the esterification,followed by the ene reaction and subsequent esterification. For theesterification of the hydroxyl group for preparation of the dimers oroligomers, it is possible to use either carboxylic acids directly oractivated carboxylic acid derivatives, for example carbonyl chloridesand anhydrides, or carboxylic esters (for a transesterificationreaction). It is also possible to use dicarboxylic acids, tricarboxylicacids and higher carboxylic acids or derivatives thereof.

The step of the ene reaction proceeding from an unsaturated fatty acidand formaldehyde (or a formaldehyde derivative, for exampleparaformaldehyde) to form the hydroxymethyl-substituted unsaturatedfatty acid derivative products with the trans-C═C double bond in theadjacent position to the hydroxymethyl substituent has already beendescribed in the literature, for example in U. Biermann, J. Metzger,Fat. Sci. Technol. 1991, 93, 282-284 and J. Metzger, U. Biermann,Synthesis 1992, 5, 463-465, and so the person skilled in the art, in theselection of the reaction conditions, can be guided by these describedstudies. For example, in U. Biermann, J. Metzger, Fat. Sci. Technol.1991, 93, 282-284, in the reaction of oleic acid as fatty acid withparaformaldehyde (2.3 equivalents), Me₂AlCl is also used as a Lewis acidadded in stoichiometric amounts at likewise 2.3 equivalents. The enereaction with different substrates has already been reported before,including in B. Snider, D. Rodini, T. Kirk, R. Cordova, J. Am. Chem.Soc. 1982, 104, 555-563, and so the person skilled in the art, in thechoice of reaction conditions, is also able to consult the reactionconditions described in these studies.

In detail, this second preferred embodiment of the process of theinvention for preparing inventive ester compounds of the general formula(I) comprises the following steps:

-   -   (A) proceeding from an unsaturated fatty acid or an ester        derived therefrom having the general formula (IV)

-   -   where R¹, R³ and n are as defined above,    -   an ene reaction and subsequent optional hydrogenation of the        resultant C═C double bond is conducted to form compounds having        the general formula (VI)

-   -   where R¹, R³, A and n are as defined above, and    -   (B) the compounds having the general formula (VI) obtained are        then subjected to an ester formation reaction using an acyl        donor having the formula (VII)

-   -   where R¹, R², R³, A and n and m are as defined above, giving        inventive compounds of the general formula (I)

-   -   where R¹, R², R³, A and n and m are as defined above.        Optionally, there can subsequently be an exchange of the R¹        group by an esterification or transesterification reaction.        Likewise optionally, in the case of a free hydroxyl group in the        R² radical, further esterification thereof is possible.

The second embodiment is presented and illustrated hereinafter using theexample of the preparation of the respective inventive compoundsproceeding from oleic acid as illustrative representative of anunsaturated fatty acid as starting compound. This example isadditionally summarized in the form of a diagram in FIG. 6. In thiscase, the reaction sequence of the individual steps involved can bevaried, so as to result in embodiments A and B described hereinafteramong others.

Proceeding from oleic acid 1, in embodiment A, an esterificationreaction is first effected, wherein, in the illustrative example,2-ethylhexan-1-ol is used as a readily available bulk chemicalobtainable in large volumes. As already stated above, there is generallya broad spectrum of methods available to the person skilled in the artfor the esterification, and one attractive synthesis option is catalyticmethods using acids or biocatalysts, preferably a lipase. The ester 2obtained in the esterification reaction is then subjected to an enereaction with paraformaldehyde in the presence of a Lewis acid, givingrise to the hydroxymethyl-substituted unsaturated fatty acid derivative6 containing a trans C═C double bond in the adjacent position to thehydroxymethyl substituent (for example, the double bond in the case ofintroduction of the hydroxymethyl function in the 9 position is then inthe 10,11 position) (FIG. 6). The subsequent hydrogenation of this C═Cdouble bond (alkene unit) adjacent to the methylol group in 6 thenaffords the saturated methylol-substituted oleic ester 4, which issubsequently converted to the desired target compounds of type 5 byacylating the hydroxyl group.

The hydroxymethyl group formed in the ene reaction may, owing to the lowor not very pronounced regioselectivity of the ene reaction, be eitherin the 9 or 10 position with corresponding positioning of the trans C═Cdouble bond in the 10,11 position (in the case of the 9 position of thehydroxymethyl group) or in the 8,9 position (in the case of the 10position of the hydroxymethyl group). Typically, a mixture of the twoisomers is contained. For reasons of clarity, FIG. 6 shows only the9-hydroxymethyl-substituted isomer with the trans C═C double bond in the10,11 position in the diagram. In the case of the products of type 5formed, particular preference is given to compounds with m′=0 or 1 to 5.

Optionally, the C═C double bonds resulting from the ene reaction canalso be hydrogenated only as a final stage after initialoligomerization. Furthermore, it is optionally additionally possiblegenerally to dispense with one or more of the hydrogenation steps, inwhich case the resulting products have at least one double bond.

In the likewise preferred embodiment B, by comparison with embodiment A,the reaction sequence is altered (FIG. 6). For instance, first of all,directly proceeding from oleic acid 1, an ene reaction is effected toobtain the compound 7, which is subsequently converted to theintermediate 4 by way of a hydrogenation of the trans C═C double bondand subsequent esterification. Optionally and alternatively, it is alsopossible first to esterify the compound 7 (which would form the compound6) and closingly to hydrogenate it, likewise giving the compound 4. Inthis case too of the ene reaction proceeding from 1, the hydroxymethylgroup formed in compound 7, owing to the low or not very markedregioselectivity of the ene reaction, may be either in the 9 or 10position with corresponding positioning of the trans C═C double bond inthe 10,11 position (in the case of the 9 position of the hydroxymethylgroup) or in the 8,9 position (in the case of the 10 position of thehydroxymethyl group). Typically, a mixture of the two isomers iscontained. For reasons of clarity, FIG. 6 shows only the9-hydroxymethyl-substituted isomer with a trans C═C double bond in the10,11 position in the diagram. The compound 4 is then, as alreadydescribed above in embodiment A, converted to the desired targetcompounds of type 5, particular preference being given to compounds withm′=0 or 1 to 5.

An illustrative representative of the preferred compound class (Ib) isthe mixture described hereinafter of the three by esterification of themixture described in example 9 cited hereinafter of two regioisomerswith 1,6-n-hexanediol as (di)alcohol component (FIG. 7). Since1,6-n-hexanediol is a diol and can thus be diesterified and, at the sametime, both the 9-substituted and the 10- substituted regioisomer of theester mixture prepared in example 9 can react with 1,6-n-hexanediol,this gives rise to a mixture of 3 regioisomers (by involvement of two9-substituted regioisomers or two 10-substituted regioisomers or one9-substituted regioisomer and one 10-substituted regioisomer in such atransesterification reaction), which is shown in FIG. 7 below. Forbetter illustration, the molecular fragment that originates from1,6-n-hexanediol in each case is shown in a box. Alternatively, suchrepresentatives of compound class (Ib) can also be prepared by thetransesterification proceeding from simple alkyl esters (such as methyland ethyl esters) or directly proceeding from the correspondingcarboxylic acids by an esterification reaction.

One illustrative representative of the preferred compound class (Ic) isthat of the mixture described hereinafter of the three by esterificationof the mixture of two regioisomers described in example 8 below withn-hexanedicarboxylic acid as (di)carboxylic acid component (FIG. 8).Since n-hexanedicarboxylic acid is a dicarboxylic acid and can thus bediesterified and, at the same time, both the 9-substituted and the10-substituted regioisomer of the ester mixture prepared in example 8can react with n-hexanedicarboxylic acid, this then gives rise to amixture of 3 regioisomers (by involvement of two 9-substitutedregioisomers or two 10-substituted regioisomers or one 9-substitutedregioisomer and one 10-substituted regioisomer in such atransesterification reaction), which is shown in FIG. 8 below. Forbetter illustration, the molecular fragment that originates fromn-hexanedicarboxylic acid in each case is shown in a box. Alternatively,such representatives of compound class (Ic) can also be prepared bytransesterification proceeding from analogous O-acylated compounds withstructurally simpler acyl components (for example acetyl, propanoyl) ordirectly proceeding from the corresponding non-O-acylated compounds witha free hydroxymethyl group by an esterification reaction.

In addition, a representative of this compound class (Ic) is themixture, described in example 13 below, of the regioisomerscorresponding to the general structure (Ic) that are present therein,which are formed from the esterification reaction of the mixture of theinvention described in example 8 with the dicarboxylic acid Pripol 1013from Croda GmbH (FIG. 9). For better illustration, the molecularfragment originating from the commercial dicarboxylic acid Pripol 1013in each case is shown in a box.

As well as n-hexanedicarboxylic acid and dimer acid (Pripol 1013),further polybasic carboxylic acids and carboxylic anhydrides are used,especially hydrogenated dimer acid, hydrogenated or unhydrogenatedtrimer acids, terephthalic acid, isophthalic acid, phthalic acid,trimellitic acid, hemimellitic acid, trimesic acid, citric acid,itaconic acid, oxalic acid, 2,2′-thiodiacetic acid, 3,3′-thiodipropionicacid, admergic acid, 2,5-furandicarboxylic acid,cyclohexane-1,4-dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid,cyclohexene-4,5-dicarboxylic acid, phenylsuccinic acid, glutamic acid,aspartic acid, ethylenediaminetetraacetic acid,diethylenetriaminepentaacetic acid, propylenediaminetetraacetic acid,nitrilotriacetic acid, diglycolic acid and iminodiacetic acid andderivatives thereof.

A further characteristic feature of the process of the invention is theinclusion of the reaction type of esterification within the scope of thepreferred embodiments of the process proceeding from unsaturated fattyacids and the synthesis sequences employed here. Various options areavailable to the person skilled in the art for the esterification ofhydroxyl groups. For instance, either the acids required may be useddirectly, or activated acid derivatives derived therefrom may be used,e.g. acid chlorides and anhydrides, or acid esters (for atransesterification reaction). A particularly attractive synthesisoption here is that of catalytic methods which permit directesterification proceeding from alcohol and acid component without theneed to use activated carboxylic acid derivatives such as carbonylchlorides and anhydrides. Such catalytic methods are known withinvolvement both of chemocatalysts and biocatalysts and are described,for example (with particular focus on biocatalysts), in G. Hills, Eur.J. Lipid Sci. Technol. 2003, 105, 601-607, O. Thum, K. M. Oxenbøll, SOFWJ. 2008, 134, 44-47, L. Hilterhaus, O. Thum, A. Liese, Org. Process Res.Dev. 2008, 12, 618-625 and M.

B. Ansorge-Schumacher, O. Thum, Chem. Soc. Rev. 2013, 42, 6475-6490. Theuse of biocatalysts is particularly attractive here since it is possibleto conduct esterification reactions in a highly efficient manner undermild reaction conditions. Correspondingly, the preparation of theinventive compounds of the general formula (I) in a synthesis method inwhich a biocatalyst selected from the enzyme class of the hydrolases isused for at least one of the esterification reactions involved is aparticularly preferred embodiment. Particularly suitable biocatalystsfrom the enzyme class of the hydrolases for the process of the inventionare lipases, and the commercially available lipase from Candidaantarctica B is a particularly suitable lipase component.

For the synthesis methods that lead to the inventive compounds of thegeneral formula (I), various possible options are available to theperson skilled in the art in the choice of reaction conditions, thesebeing described in detail in the literature for the individual reactiontypes involved. Among other parameters, the person skilled in the art isfree to choose the respective reaction media and may make use, forexample, of a broad spectrum of solvents for performance of thesynthesis reactions in the process of the invention. However, it isparticularly advantageous with regard to the sustainability of thepreparation process to avoid solvents. Especially for esterificationreactions, solvent-free syntheses have already been described asefficient in the literature, for example in the already above-citedcontributions G. Hills, Eur. J. Lipid Sci. Technol. 2003, 105, 601-607,O. Thum, K. M. Oxenbøll, SOFW J. 2008, 134, 44-47, L. Hilterhaus, O.Thum, A. Liese, Org. Process Res. Dev. 2008, 12, 618-625 and M. B.Ansorge-Schumacher, O. Thum, Chem. Soc. Rev. 2013, 42, 6475-6490. Sincethe reaction type of esterification is also a characteristic feature ofthe process of the invention, the preparation of the inventive compoundsof the general formula (I) in a synthesis method in which at least oneof the esterification reactions involved is effected under solvent-freereaction conditions is a particularly preferred embodiment.

A particular technical advantage of the process of the inventiondeveloped and of the products having an O-acylated methylol functionthus obtained is the presence of a primary alcohol function in theparent hydroxymethylol-substituted fatty acid esters as substrate. Thisfunctional primary amino group is highly suitable for enzyme-catalyticreactions under mild preparation conditions and at low temperatures, andhence enables the preparation of the desired compounds underenvironmentally friendly conditions with simultaneously low energyconsumption.

A further general technical advantage of the compounds of the inventionand of the preparation process of the invention lies in the enormouslyhigh selectivity. The estolide compounds disclosed in DE 698 35 694 T2cannot be prepared in this selectivity since the reaction linkage hereproceeds from an unsaturated fatty acid as base unit by addition of thefatty acid unit of this base unit onto the alkene unit of the next baseunit, and hence di-, tri-, tetra- or generally oligomers and evenpolymers are formed as a mixture. In the process of the invention, byvirtue of mild reaction conditions and highly selective enzymereactions, but also by virtue of the strategy of the reaction regime,preferably only monofunctionalization of the methylol component of thestarting compound is achieved in each case (said starting compoundconsisting, for example, of a mixture of a 9- and10-methylol-substituted fatty acid ester). Furthermore, the tailoredpreparation of more highly substituted trimers and tetramers is alsoconceivable in a selective manner by correspondingly controlledsyntheses. Therefore, the target compounds are obtained with highselectivity in defined form with avoidance of higher oligomeric orpolymeric structures, in a way which is not possible with the knownmethods, by which complex product mixtures are obtained.

The inventive ester compounds of the general formula (I) are ofexcellent suitability for use in lubricant compositions and are suitablefor use both in the high-temperature sector and in the marine sector,and as lubricant which is used in the foods sector.

As well as the novel ester compounds, the lubricant compositions of theinvention may especially contain further base oil components, especiallybased on natural glyceride esters and fatty acids, preferably sunfloweroil, rapeseed oil or colza oil, linseed oil, corn oil or corn germ oil,safflower oil, soybean oil, linseed oil, groundnut oil, “lesquerella”oil, palm oil, olive oil, in the monomeric, oligomeric and/orpolymerized forms or mixtures of the oils mentioned.

In addition, the lubricant compositions of the invention, as well as thenovel ester compounds, may contain further esters such astrimethylolpropane and pentaerythritol esters, and also TMP complexesters, in fully or partly esterified form with saturated and/or mono-or polyunsaturated carboxylic acids of chain length C6-C36, where thesemay be linear or branched, complex esters of dimer acids, dimer acidesters such as ethylhexyl dimerate, aliphatic carboxylic anddicarboxylic esters, and also phosphate esters, trimellitic andpyromellitic esters, ethers, polyether polyols and perfluoropolyethers,alkyl diphenyl ethers and polyphenyl ethers, silicone oils, polyglycolsconsisting of randomly distributed polyoxyethylene and/orpolyoxypropylene units and/or other polyoxyalkylene units, and otherglycol derivatives, polyalphaolefins including those prepared bymetallocene catalysis, and alpha-olefin copolymers, polymeric systems,for example unhydrogenated, partly hydrogenated or fully hydrogenatedpolyisobutylene or a mixture thereof, styrene and polystyrene and theirderivatives and/or polymeric systems based on acrylates, acetatepolymers and amides, polyethylenes, polypropylenes, halogenatedpolypropylenes and/or cycloalkanes, mineral oils, for example white oil,alkylated diphenyl ethers, alkylated naphthalenes andperfluoropolyethers.

The lubricant containing the inventive ester compound of the generalformula (I) may be used either in the form of a lubricant oil or alubricant grease.

The lubricant further comprises additives that may be used individuallyor in combination and are selected from the group consisting ofanticorrosion additives, antioxidants, antiwear additives, UVstabilizers, inorganic or organic solid lubricants, pour point and VIimprovers, polymers, adhesion additives, dyes, emulsifiers, defoamersand solid lubricants that are typical for the formulation of a lubricantoil or lubricant grease.

Lubricant greases may be produced with different thickeners. Onepossible group of thickeners is that of ureas consisting of the reactionproduct of a diisocyanate, preferably 2,4-diisocyanatotoluene,2,6-diisocyanatotoluene, 4,4′-diisocyanatodiphenylmethane,2,4′-diisocyanatophenylmethane, 4,4′-diisocyanatodiphenyl,4,4′-diisocyanato-3,3′-dimethylphenyl,4,4′-diisocyanato-3,3′-dimethylphenylmethane, which may be usedindividually or in combination, with an amine of the general formulaR′₂—N—R, or a diamine of the general formula R′₂—N—R—NR′₂, where R is anaryl, alkyl or alkylene radical having 2 to 22 carbon atoms and R′ isidentical or different and is a hydrogen, an alkyl, alkylene or arylradical, or with mixtures of amines and diamines, or as thickener arepresentative is selected from the group of the Al complex soaps,simple metal soaps of the elements of the first and second main groupsof the Periodic Table, complex metal soaps of the elements of the firstand second main groups of the Periodic Table, bentonites, sulfonates,silicates, aerosil, polyimides or PTFE or a mixture of theaforementioned thickeners.

In order to meet the legal requirements with regard to the use oflubricants for lubrication of machinery for the processing of foods, itis appropriate when the additives used have an H1 classification.

The addition of antioxidants can reduce or even prevent the oxidation ofthe oil or grease of the invention, especially in use. Correspondingly,the addition of antioxidants is a further preferred embodiment of theprocess of the invention. The antioxidants are selected from the groupconsisting of diaromatic amines, phenol resins, thiophenol resins,phosphites, butylated hydroxytoluene, butylated hydroxyanisole,phenyl-α-naphthylamines, phenyl-β-naphthylamines, octylated/butylateddiphenylamines, di-α-tocopherol, di-tert-butyl-phenyl, benzenepropanoicacid and mixtures of these components.

The lubricant of the invention may contain anticorrosion additives,metal deactivators or ion complexing agents. These include triazoles,imidazolines, N-methylglycine (sarcosine), benzotriazole derivatives,N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine;N-methyl-N-(1-oxo-9-octadecenyl)-glycine, mixture of phosphoric acid andits mono- and diisooctyl esters with (C11-14)-alkylamines, mixtures ofphosphoric acid and mono- and diisooctyl esters reacted withtert-alkylamines and primary (C12-14) amines, dodecanoic acid, triphenylphosphorothionate and amine phosphates. Commercially available additivesare, for example, the following products: IRGAMET® 39, IRGACOR® DSS G,Amin O; SARKOSYL® O (Ciba), COBRATEC® 122, CUVAN® 303, VANLUBE® 9123,CI-426, CI-426EP, CI-429 and CI-498.

The lubricant of the invention may additionally contain antiwearadditives, antiwear additives and friction modifiers.

Antiwear additives are amines, amine phosphates, phosphates,thiophosphates, phosphorothionates, aryl phosphate, alkylatedpolysulfides, sulfurized amine compounds, sulfurized fatty acid methylesters, naphthenic acids, nanoparticles from the groups of Al₂O₃, SiO₂,TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC,Si₃N₄, TiC, TiN, ZrB₂, clay minerals and/or mixtures thereof, and alsothermally stable carbonates and/or sulfates, and mixtures of thesecomponents. The commercially available antiwear additives includeIRGALUBE® TPPT, IRGALUBE® 232, IRGALUBE® 349, IRGALUBE® 211 and ADDITIN®RC3760 Liq 3960, FIRC-SHUN® FG 1505 and FG 1506, NA-LUBE® KR-015FG,LUBEBOND®, FLUORO® FG, SYNALOX® 40-D, ACHESON® FGA 1820 and ACHESON® FGA1810.

The lubricant of the invention may contain pour point and viscosityimprovers and adhesion additives. Pour point and viscosity improvers areselected from the groups of the linear and/or branched alkylated,acrylated and aliphatic polymers and copolymers, and polymerized fattyacid esters, for instance from the group of PIBs (polyisobutylenes) andPBs (polybutenes) in partly or fully hydrogenated form.

The lubricant of the invention may further contain UV stabilizers. UVstabilizers are selected from the groups of the nitrogen heterocycles,substituted nitrogen heterocycles, linear and branched alkylated,acylated, aliphatic nitrogen heterocycles, and derivatives thereof.

The lubricant of the invention may also contain solid lubricants. Solidlubricants are, for example, PTFE, BN, pyrophosphate, Zn oxide, Mgoxide, pyrophosphates, thiosulfates, Mg carbonate, Ca carbonate, Castearate, Zn sulfide, Mo sulfide, W sulfide, Sn sulfide, graphite,graphene, nanotubes, SiO₂ polymorphs or a mixture thereof.

The lubricant of the invention may contain emulsifiers. Emulsifiers areselected from the groups of the branched and/or linear ethoxylatedand/or propoxylated alcohols and salts thereof, for example alcohols,C16-C18, ethoxylated, propoxylated, polyglycols, fatty acid esters,silicates, ionic surfactants, for example sodium salts of alkylsulfonicacids, where the chains contain C14-17 carbons.

The lubricant of the invention may contain defoamers. Defoamers areselected from the groups of the ethoxylated and/or propoxylated alcoholsof chain lengths C10-C18, mono- and diglycerides of cooking fats,acrylates, propoxylated and/or ethoxylated alkyl ethers (polyglycols),alcohols, siloxanes.

A preferred form of the preparation method for an oil formulation is asfollows: the vessel is initially charged with the ester compound of thegeneral formula (I). The viscosity-imparting component and/or one ormore further base oils are added, and a clear solution is produced withstirring and optionally heating to a defined temperature. Solidadditives are then added at a temperature above their melting point andstirred until they have dissolved. Subsequently, the contents of thevessel are cooled down to not more than 60° C. and the liquid additivesare added. After a further hour of stirring time, the oil can bedispensed.

In a preferred form of the preparation method for a grease formulation,the procedure is additionally as follows: the vessel is initiallycharged with the base oil mixture. The thickener components are added ina defined manner at a defined temperature while stirring. The greasethus formed is stirred for a defined period of time and, specifically inthe case of use of soap-based thickeners, boiled until it is free ofwater. Solid additives are then added at a temperature above theirmelting point and stirred until they have dissolved. Subsequently, thecontents of the vessel are cooled down to not more than 60° C. and theliquid additives are added. After a further hour of stirring time, thegrease can be dispensed.

The lubricant compositions of the invention based on the ester compoundof the general formulae (I), for example the ester compound of thegeneral formulae (Ia) or (Ib) or (Ic), are used in the marine sector, inthe inland waterways sector and in offshore facilities, i.e. forlubrication of chains, ball bearings, propeller rudders, propellershafts, machine components and facilities that come into contact withsaltwater in the marine sector or with water and aqueous media in inlandwaterways. Furthermore, they find use in the lubrication of machinery inthe food processing industry, as hydraulic oil in the food processingindustry, for transport and control chains, for apparatuses for theprocessing of cereal, flour and animal feed, and in baking ovens. Theyare also used for lubrication of roller bearings and slide bearings,transport and control chains in vehicle technology, in conveyingtechnology, in mechanical engineering, in office technology and inindustrial plants and machinery, and in the sectors of domesticappliances and consumer electronics. Furthermore, they are used forlubrication of bevel gears and spur gears of roller bearings incontinuous casting plants and transport bearings in continuous kilns andfor open crown gear lubrication in rotary kilns, tubular mills, drumsand mixers, such as specifically in the cement, lime, gypsum, mining andchemical industries.

It should additionally be noted that the compounds of the invention, ifthey contain stereocenters, may either be racemic or enantiomericallyenriched or enantiomerically pure compounds.

The section which follows elucidates the ester compounds of theinvention and the preparation thereof, and also the use thereof in alubricant composition, using corresponding experimental examples.

EXAMPLES

General Experimental Method 1 (GEM1): Biocatalytic Synthesis of OleicEsters Proceeding From Oleic Acid and Guerbet Alcohols

To an initial charge of oleic acid (1.0 eq.) and Guerbet alcohol (1.0eq.) were added CAL-B (Novozym 435, 30 mg/mmol substrate) and 4 Amolecular sieve (120 mg/mmol). The reaction mixture was stirred at 50°C. for 24 hours and then filtered through a 0.2 μM PTFE filter. Thecorresponding oleic ester was obtained in product purity 97-99%.

Example 1 Preparation of 2-ethylhexyl oleate proceeding from oleic acidand 2-ethylhexan-1-ol

The synthesis was according to GEM 1. To oleic acid (31.6 ml, 100 mmol)and 2-ethylhexan-1-ol (15.6 ml, 100 mmol) were added Novozym 435 (3.0 g)and 4 Å molecular sieve (12.0 g). 2-Ethylhexyl oleate (99% purity) wasobtained as a colorless liquid.

Yield: 37.3 g, 95%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.34 (m, 2H, CH═CH), 3.98 (dd, 2H,²J=5.8 Hz, ³J=2.4 Hz, OCH₂), 2.29 (t, 2H, ³J=7.5 Hz, CH₂CH₂COOR), 2.01(m, 4H, CH₂CH═CHCH₂), 1.61 (qi, 2H, ³J=7.3 Hz, CH₂CH₂COOR), 1.56 (sept,1H, ³J=6.0 Hz, OCH2CH), 1.28 (m, 28H), 0.88 (m, 9H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ[ppm]=174.21, 130.11, 129.87, 66.76, 38.90,34.58, 32.05, 30.57, 29.91, 29.84, 29.67, 29.47, 29.33, 29.29, 29.26,29.07, 27.36, 27.31, 25.19, 23.95, 23.12, 22.83, 14.25, 14.18.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C/min), 350° C. for 5 min,R_(t)=3.51 min.

HRMS (ESI): calculated for C₂₆H₅₀O₂Na [M+Na]⁺: 417.3703, found:417.3699.

IR (neat) [cm⁻¹]: 2956, 2922, 2853, 1736, 1461, 1240, 1171, 724.

Example 2 Preparation of 2-butyloctyl oleate proceeding from oleic acidand 2-butyloctan-1-ol

The synthesis was according to GEM 1. To oleic acid (1.59 ml, 5.00 mmol)and 2-butyloctan-1-ol (1.12 ml, 5.00 mmol) were added Novozym 435 (150mg) and 4 Å molecular sieve (600 mg). 2-Butyloctyl oleate (97% purity)was obtained as a colorless liquid.

Yield: 1.30 g, 58%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.34 (m, 2H, CH═CH), 3.96 (d, 2H,²J=5.8 Hz, OCH₂), 2.29 (t, 2H, ³J=7.5 Hz, CH₂CH₂COOR), 2.01 (m, 4H,CH₂CH═CHCH₂), 1.61 (m, 2H, CH₂CH₂COOR), 1.60 (m, 1H, OCH₂CH), 1.28 (m,36H), 0.88 (m, 9H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.21, 130.11, 129.87, 67.16, 37.43,34.60, 32.06, 31.97, 31.44, 31.11, 29.92, 29.86, 29.78, 29.68, 29.47,29.35, 29.31, 29.28, 29.07, 27.36, 27.32, 26.82, 25.21, 23.14, 22.83,22.81, 14.25, 14.24, 14.19.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C./min), 350° C. for 5 min;R_(t)=4.27 min.

HRMS (ESI): calculated for C₃₀H₅₈O₂Na [M+Na]⁺: 473.4329, found:473.4324.

IR (neat) [cm⁻¹]: 2954, 2922, 2853, 1737, 1457, 1241, 1169, 723.

Example 3 Preparation of 2-hexyldecyl oleate proceeding from oleic acidand 2-hexyldecan-1-ol

The synthesis was according to GEM 1. To oleic acid (1.59 ml, 5.00 mmol)and 2-hexyldecan-1-ol (1.44 ml, 5.00 mmol) were added Novozym 435 (150mg) and 4 Å molecular sieve (600 mg). 2-Hexyldecyl oleate (97% purity)was obtained as a colorless liquid.

Yield: 1.51 g, 60%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.34 (m, 2H, CH═CH), 3.97 (d, 2H,²J=5.8 Hz, OCH₂), 2.29 (t, 2H, ³J=7.5 Hz, CH₂CH₂COOR), 2.01 (m, 4H,CH₂CH═CHCH₂), 1.61 (m, 2H, CH₂CH₂COOR), 1.60 (m, 1H, OCH₂CH), 1.28 (m,44H), 0.88 (m, 9H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.22, 130.12, 129.87, 67.18, 37.45,34.61, 32.06, 31.97, 31.44, 30.12, 29.92, 29.86, 29.78, 29.72, 29.68,29.48, 29.36, 29.32, 29.29, 27.37, 27.32, 26.86, 26.82, 25.21, 22.84,22.81, 14.26, 14.25.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C./min), 350° C. for 5 min;R_(t)=5.65 min.

HRMS (ESI): calculated for C₃₄H₆₆O₂Na [M+Na]⁺: 529.4955, found:529.4951.

IR (neat) [cm⁻¹]: 2921, 2852, 1737, 1464, 1169, 722.

Example 4 Preparation of 2-octyldodecyl oleate proceeding from oleicacid and 2-octyldocecan-1-ol

The synthesis was according to GEM 1. To oleic acid (1.59 ml, 5.00 mmol)and 2-octyldodecan-1-ol (1.78 ml, 5.00 mmol) were added Novozym 435 (150mg) and 4 Å molecular sieve (600 mg). 2-Octyldodecyl oleate (98% purity)was obtained as a colorless liquid.

Yield: 1.67 g, 59%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.34 (m, 2H, CH═CH), 3.97 (d, 2H,²J=5.8 Hz, OCH₂), 2.29 (t, 2H, ³J=7.5 Hz, CH₂CH₂COOR), 2.01 (m, 4H,CH₂CH═CHCH₂), 1.61 (m, 2H, CH₂CH₂COOR), 1.60 (m, 1H, OCH₂CH), 1.28 (m,52H), 0.88 (m, 9H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.22, 130.12, 129.87, 67.19, 37.43,34.61, 32.08, 32.07, 31.42, 30.12, 29.92, 29.87, 29.82, 29.81, 29.77,29.72, 29.69, 29.52, 29.48, 29.36, 29.32, 29.29, 27.37, 27.32, 26.85,25.21, 22.84, 14.27.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C./min), 350° C. for 5 min;R_(t)=7.70 min.

HRMS (ESI): calculated for C₃₄H₆₆O₂Na [M+Na]⁺: 585.5581, found:585.5568.

IR (neat) [cm⁻¹]: 2920, 2852, 1737, 1464, 1170, 722.

General Experimental Method 2 (GEM2): Ene Reaction of Oleic Acid/Esterwith Paraformaldehyde and Lewis acids

In accordance with experimental methods of Metzger and Biermann (U.Biermann, J. Metzger, Fat. Sci. Technol. 1991, 93, 282-284; J. Metzger,U. Biermann, Synthesis 1992, 5, 463-465), an initial charge of oleicacid (1.0 eq.) or its 2-ethylhexyl ester (1.0 eq.) and paraformaldehyde(2.3 eq.) under argon in dry dichloromethane was cooled to 0° C.Subsequently, EtAlCl₂ or Me₂AlCl (2.3-3.3 eq., 1.0 M in n-hexane) wasadded dropwise and the reaction mixture was then warmed gradually toroom temperature and stirred for two hours. Water (1:1 v/v) was addedand the mixture was acidified to pH=1 with 4 M HCl. The phases wereseparated and the aqueous phase was extracted three times with diethylether (1:1 v/v). The combined extracts were dried over magnesium sulfateand freed of the solvent under reduced pressure. Subsequent columnchromatography gave the products as colorless oils. The products wereobtained as a 1:1 mixture of the C9 and C10 adducts.

Example 5 Preparation of a mixture ofE-9-(hydroxymethyl)octadec-10-enoic acid andE-10-(hydroxymethyl)octadec-8-enoic acid

The synthesis was according to GEM 2. Oleic acid (4.73 ml, 15 mmol) andparaformaldehyde (1.04 g, 34.5 mmol) were reacted with addition ofMe₂AlCl (34.5 ml, 34.5 mmol). Workup and column chromatography(cyclohexane/ethyl acetate 7:3, v/v) gave the product as a colorlessliquid.

Yield: 1.50 g, 32%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.52 (m, 1H, CH═CHCH), 5.13 (m, 1H,CH═CHCH), 3.52 (m, 1H, CH₂OH), 3.33 (m, 1H, CH₂OH), 2.34 (2 t, 2H,³J=7.5 Hz, CH₂COO), 2.15 (m, 1H, CH═CHCH), 2.04 (m, 2H, CH₂CH═CH), 1.64(m, 2H, CH₂CH₂COO), 1.27 (m, 22H), 0.88 (2 t, 3H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=179.15, 179.07, 134.33, 133.88,131.64, 131.30, 66.15, 66.10, 46.06, 34.01, 34.01, 32.82, 32.68, 32.03,32.01, 31.27, 31.21, 29.82, 29.69, 29.68, 29.57, 29.45, 29.37, 29.29,29.28, 29.26, 29.16, 28.99, 28.79, 27.24, 27.15, 27.07, 24.80, 24.75,22.82, 22.81, 14.25.

The analytical data corresponded to the literature (J. Metzger, U.Biermann, Synthesis 1992, 5, 463-465).

Example 6 Preparation of a mixture of 2′-ethylhexylE-9-(hydroxymethyl)octadec-10-enoate and 2′-ethylhexylE-10-(hydroxymethyl)octadec-8-enoate

The synthesis was according to GEM 2. 2-Ethylhexyl oleate (23.7 g, 60mmol) and paraformaldehyde (4.14 g, 138 mmol) were reacted with additionof EtAlCl₂ (198 ml, 198 mmol). Workup and vacuum distillation (at 10⁻³mbar) gave the product as a colorless liquid.

Yield: 17.6 g, 69%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.51 (m, 1H, CH═CHCH), 5.12 (m, 1H,CH═CHCH), 3.98 (m, 2H, COOCH₂), 3.51 (m, 1H, CH₂OH) 3.32 (m, 1H, CH₂OH),2.29 (2 t, 2H, ³J=7.5 Hz, CH₂COO), 2.12 (m, 1H, CH═CHCH), 2.02 (m, 2H,CH₂CH═CH), 1.61 (m, 2H, CH₂CH₂COO), 1.56 (m, 1H, OCH₂CH), 1.27 (m, 28H),0.88 (3 t, 9H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.21, 174.18, 134.27, 133.90,131.58, 131.33, 66.79, 66.77, 66.12, 66.09, 46.09, 38.88, 34.56, 34.54,32.81, 32.72, 32.02, 31.99, 31.25, 31.23, 30.56, 29.81, 29.67, 29.67,29.64, 29.46, 29.44, 29.34, 29.28, 29.24, 29.10, 29.06, 28.90, 27.23,27.18, 25.16, 25.12, 23.93, 23.12, 22.81, 22.80, 14.25, 14.24, 14.19,11.13.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C./min), 350° C. for 5 min;R_(t)=4.29, 4.53 min.

HRMS (ESI): calculated for C₂₇H₅₂O₃Na [M+Na]⁺: 447.3809, found:447.3813.

IR (neat) [cm⁻¹]: 2923, 2854, 1733, 1462, 1379, 1171, 1032, 969.

General experimental method 3 (GEM3): Palladium-catalyzed C═Chydrogenation of the unsaturated oleic acid derivatives

The unsaturated free acid (1.0 eq.) or the 2-ethylhexyl ester (1.0 eq.)was dissolved in cyclohexane under a hydrogen atmosphere and admixedwith palladium on activated charcoal (Pd/C, 10% Pd, 20% by weight). Thereaction mixture was stirred at room temperature for two hours and thenfiltered through a 0.2 μM PTFE filter. Column chromatography gave thedesired product as a colorless oil.

Example 7 Preparation of a mixture of 9-(hydroxymethyl)octadecanoic acidand 10-(hydroxymethyl)octadecanoic acid

The synthesis was conducted according to GEM 3. A mixture ofE-9-(hydroxymethyl)octadec-10-enoic acid andE-10-(hydroxymethyl)octadec-8-enoic acid (450 mg, 1.44 mmol) wasdissolved under a hydrogen atmosphere in 25 ml of cyclohexane andadmixed with Pd/C (90 mg). Workup and column chromatography(cyclohexane/ethyl acetate 1:2, v/v) gave the desired product as acolorless oil.

Yield: 130 mg, 25%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=3.53 (d, 2H, ³J=5.5 Hz CH2OH), 2.35 (t,2H, ³J=7.5 Hz, CH₂COO), 1.63 (qi, 2H, ³J=7.3 Hz, CH2CH₂COO), 1.45 (m,1H, HOCH₂CH), 1.27 (m, 36H), 0.88 (t, 3H, ³J=6.9 Hz, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=179.62, 65.81, 65.79, 40.59, 34.15,34.14, 32.05, 31.07, 31.02, 30.99, 30.22, 30.05, 29.91, 29.80, 29.78,29.76, 29.49, 29.30, 29.15, 29.13, 27.04, 26.92, 26.88, 24.80, 22.83,14.27.

HRMS (ESI): calculated for C₁₉H₃₈O₃Na [M+Na]⁺: 337.2713, found:337.2717.

IR (neat) [cm⁻¹]: 2913, 2848, 1699, 1469, 1185, 972, 719.

Example 8 Preparation of a mixture of 2′-ethylhexyl9-(hydroxymethyl)octadecanoate and 2′-ethylhexyl10-(hydroxymethyl)octadecanoate

The synthesis was conducted according to GEM 3. A mixture of2′-ethylhexyl E-9-(hydroxymethyl)octadec-10-enoate and 2′-ethylhexylE-10-(hydroxymethyl)octadec-8-enoate (1.06 g, 2.50 mmol) was dissolvedunder a hydrogen atmosphere in 50 ml of cyclohexane and admixed withPd/C (212 mg). Workup and column chromatography (cyclohexane/ethylacetate 7:1, v/v) gave the desired product as a colorless oil.

Yield: 660 mg, 62%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=3.97 (m, 2H, COOCH₂), 3.54 (d, 2H,³J=5.5 Hz CH₂OH), 2.29 (t, 2H, ³J=7.5 Hz, CH₂COO), 1.61 (m, 2H,CH₂CH₂COO), 1.56 (m, 1H, OCH₂CH), 1.27 (m, 36H), 0.89 (3 t, 9H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.27, 174.26, 66.79, 65.85, 65.83,40.67, 38.90, 34.60, 34.58, 32.05, 31.08, 31.07, 31.05, 30.57, 30.22,30.14, 30.02, 29.81, 29.78, 29.76, 29.59, 29.49, 29.41, 29.40, 29.30,29.07, 27.05, 27.01, 26.97, 25.19, 23.95, 23.13, 22.83, 14.27, 14.20,11.15.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C/min), 350° C. for 5 min;R_(t)=4.61 min.

HRMS (ESI): calculated for C₂₇H₅₄O₃Na [M+Na]⁺: 449.3965, found:449.3975.

IR (neat) [cm⁻¹]: 2921, 2853, 1736, 1459, 1171, 1031.

Example 9 Preparation of a mixture of 2′-ethylhexyl9-((stearoyloxy)methyl)octadecanoate and 2′-ethylhexyl10-((stearoyloxy)methyl)octadecanoate

The synthesis was conducted according to GEM 3. A mixture of2′-ethylhexyl E-9-(hydroxymethyl)octadec-10-enoate and 2′-ethylhexylE-10-(hydroxymethyl)octadec-8-enoate (2.00 g, 2.90 mmol) was dissolvedunder a hydrogen atmosphere in 50 ml of cyclohexane and admixed withPd/C (400 mg). Workup and column chromatography (cyclohexane/ethylacetate 15:1, v/v) gave the desired product as a colorless oil.

Yield: 1.62 g, 81%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=3.97 (m, 4H, COOCH₂), 2.28 (t, 4H,³J=7.5 Hz, CH₂COO), 1.61 (m, 6H, CH₂CH₂COO), 1.25 (m, 62H), 0.89 (m,12H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.22, 174.16, 67.13, 66.75, 38.91,37.46, 34.60, 34.58, 32.07, 31.42, 30.58, 30.12, 30.06, 29.94, 29.85,29.81, 29.76, 29.71, 29.65, 29.63, 29.58, 29.46, 29.43, 29.39, 29.34,29.32, 29.07, 26.85, 25.21, 23.95, 23.12, 22.84, 14.25, 14.18, 11.13.

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C./min), 350° C. for 5 min;R_(t)=14.4 min.

HRMS (ESI): calculated for C₄₅H₈₈O₄Na [M+Na]⁺: 715.6575, found:715.6573.

IR (neat) [cm⁻¹]: 2921, 2852, 1736, 1463, 1169.

TABLE 1 Chemical and physical properties of the product prepared byexample 9 Product prepared Parameter Method Unit by example 9 Appearanceliquid clear colorless Kin. vis. 40° C. ASTM mm²/s 29.8 Kin. vis. 100°C. D 7042 6.56 VI 184.1 Biodegradability OECD % 81.3 301 F

General Experimental Method 4 (GEM4): Biocatalytic Esterification ofFatty Acids with Hydroxymethylated Stearic Acid Derivatives to Give“Dimers”

The hydroxymethylated 2′-ethylhexyl stearate (1.0 eq.) was dissolved inMTBE and admixed with Novozym 435 (CAL-B, 30 mg/mmol) and 4 A molecularsieve (120 mg/mmol) and a fatty acid (1.0 eq.). The reaction mixture wasstirred at 50 to 60° C. for 24 hours and then filtered through a 0.2 μMPTFE filter. Removing the solvent under reduced pressure gave theproduct as a colorless oil.

Example 10 Preparation of a mixture of 2′-ethylhexyl9-((stearoyloxy)methyl)octadecanoate and 2′-ethylhexyl10-((stearoyloxy)methyl)octadecanoate

The synthesis was according to GEM 4. A mixture of 2′-ethylhexyl 9- and2′-ethylhexyl 10-(hydroxymethyl)octadecanoate (51.7 mg, 100 μmol) andstearic acid (28.4 mg, 100 μmol) were dissolved in 50 μl of MTBE andadmixed with Novozym 435 (3 mg) and 4 Å molecular sieve (12 mg) andstirred at 50° C. Workup gave the desired product as a colorless oil.

Yield: 58 mg, 85%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=3.98 (m, 2H, COOCH₂), 3.95 (m, 2H,COOCH₂), 2.29 (2 t, 4H, ³J=7.4 Hz, CH₂COO), 1.61 (m, 4H, CH2CH₂COO),1.56 (m, 2H, OCH₂CH), 1.27 (m, 62H), 0.89 (4 t, 12H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.29, 174.27, 174.22, 67.16, 66.78,38.91, 37.46, 34.63, 34.60, 34.59, 32.08, 32.07, 31.43, 30.58, 30.13,29.86, 29.83, 29.82, 29.77, 29.72, 29.66, 29.64, 29.52, 29.51, 29.48,29.44, 29.35, 29.33, 29.08, 26.86, 25.22, 25.21, 23.96, 23.14, 22.85,14.28, 14.21, 11.15.

The analytical data correspond to those of the compound of example 9.

Example 11 Preparation of a mixture of 2′-ethylhexyl9-((stearoyloxy)methyl)octadec-10-enoate and 2′-ethylhexyl10-((stearoyloxy)methyl)octadec-8-enoate

A mixture of 2′-ethylhexyl E-9-(hydroxymethyl)octadec-10-enoate and2′-ethylhexyl E-10-(hydroxymethyl)octadec-8-enoate

(10.0 g, 23.5 mmol) was mixed with stearic acid (6.70 g, 23.5 mmol) andheated to 70° C., which melted the stearic acid. Novozym 435 (CAL-B, 706mg, 30 mg/mmol) and 4 Å molecular sieve (3.3 g, 120 mg/mmol) were added.The reaction mixture was stirred at 70° C. for 24 hours. Subsequently,it was filtered through a 0.2 μM PTFE filter.

Removing the solvent in vacuo and filtration through silica gel(cyclohexane/ethyl acetate 15:1, v/v) gave the product as a colorlessoil.

Yield: 11.9 g, 73%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.40 (m, 1H, CH═CH), 5.14 (m, 1H,CH═CH), 3.98 (m, 2H, COOCH₂), 2.29 (m, 4H, CH₂COO), 1.97 (m, 2H, CHCH₂)1.61 (m, 5H, CH₂CH₂COO+OCH₂CH), 1.27 (m, 60H), 0.88 (4 t, 12H, CH₃).

GC (FID): Phenomenex ZB-5MSi, 0.5 ml/min (H2), inj. temp.: 300° C., det.temp.: 350° C.; 300° C.→350° C. (5° C./min), 350° C. for 5 min;R_(t)=14.1 min.

HRMS (ESI): calculated for C₄₅H₈₆O₄Na [M+Na]⁺: 713,6418, found:713,6419.

IR (neat) [cm⁻¹]: 2959, 2926, 2856, 1736, 1257, 1011, 865, 790, 700.

Example 12 Preparation of a mixture of 2′-ethylhexyl9-((octadec-9-enoyloxy)methyl)octadecanoate and 2′-ethylhexyl10-((octadec-9-enoyloxy)methyl)octadecanoate

The synthesis was according to GEM 4. A mixture of 2′-ethylhexyl9-(hydroxymethyl)octadecanoate and 2″-ethylhexyl10-(hydroxymethyl)octadecanoate (51.7 mg, 100 μmol) and oleic acid (28.2mg, 100 μmol) were admixed with Novozym 435 (3 mg) and 4 A molecularsieve (12 mg) and stirred at 60° C. Workup gave the desired product as acolorless oil.

Yield: 39 mg, 56%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.34 (m, 2H, CH═CH), 3.98 (m, 2H,COOCH₂), 3.95 (m, 2H, COOCH₂), 2.29 (2 t, 4H, ³J=7.4 Hz, CH₂COO), 1.61(m, 4H, CH₂CH₂COO), 1.56 (m, 2H, OCH₂CH), 1.27 (m, 58H), 0.89 (4 t, 12H,CH₃).

MS (ESI): m/z=691.5 [M+H]⁺.

IR (neat) [cm⁻¹]: 2959, 2926, 2856, 1736, 1257, 1011, 865, 790, 700.

Example 13 Preparation of a mixture of 2′-ethylhexyl9-(((12-hydroxyoctadecanoyl)-oxy)methyl)octadecanoate and 2′-ethylhexyl10-(((12-hydroxyoctadecanoyl)-oxy)methyl)octadecanoate

The synthesis was according to GEM 4. A mixture of 2′-ethylhexyl9-(hydroxymethyl)octadecanoate and 2′-ethylhexyl10-(hydroxymethyl)octadecanoate (213.2 mg; 500 μmol), and12-hydroxystearic acid (142.8 mg; 480 μmol) were stirred with 4 Amolecular sieve (59.53 mg), Novozym 435 (14.5 mg) and MTBE (0.5 ml) at50° C. for 24 h. Workup gave the desired product as a colorless oil.

Yield: 267 mg, 76%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=4.05-3,86 (m, 4H, COOCH₂); 3.58 (dt,1H, ³J=7.4, 4.2 Hz, CH₂OH); 2.29 (t, 4H, ³J=7.5 Hz, CH₂COO); 1.58 (dt,6H, ³J=24,3, 6,6 Hz); 1.41 (d, 6H, ³J=6.5 Hz); 1,37-1,20 (m, 55H); 0.88(td, 12H, ³J=6.9, 6.3, 3.8 Hz, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.22, 150.97, 67.14, 66.78, 38.91,37.63, 37.46, 34.59, 32.05, 31.99, 31.43, 30.58, 30.11, 29.85, 29.83,29.75, 29.73, 29.69, 29.66, 29.61, 29.58, 29.52, 29.49, 29.46, 29.43,29.40, 29.32, 29.30, 29.07, 26.84, 25.79, 25.76, 25.19, 23.95, 23.12,22.82, 22.76, 14.24, 14.22, 14.18, 11.13.

HRMS (ESI): calculated for C₄₅H₈₈O₅Na⁺: 731.6524; found: 731.6521.

Example 14 Preparation of a mixture of(E)-11-((2-ethylhexyl)oxy)-2-octyl-11-oxoundec-3-en-1-yl((E)-2-(8-((2-ethylhexyl)oxy)-8-oxooctyl)undec-3-en-1-yl)adipate,bis((E)-11-((2-ethylhexyl)oxy)-2-octyl-11-oxoundec-3-en-1-yl) adipateand bis((E)-2-(8-((2-ethylhexyl)oxy)-8-oxooctyl)undec-3-en-1-yl)adipate

The synthesis was in accordance with GEM 4. To a mixture of2′-ethylhexyl E-9-(hydroxymethyl)octadec-10-enoate and 2′-ethyl hexylE-10-(hydroxymethyl)octadec-8-enoate (999.6 mg, 2.4 mmol) and adipicacid (172.6 mg, 1.2 mmol) were added Novozym 435 (70.6 mg) and 4 Åmolecular sieve (288 mg), and the mixture was stirred at 60° C. Workupgave the desired product as a yellowish oil.

Yield: 1.06 g, 94%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.43 (m, 2H, CH═CH), 5.19-5.09 (m, 2H,CH═CH), 4.07-3.86 (m, 8H, COOCH₂), 2.29 (m, 8H, CH₂COO), 1.98 (m, 4H,CHCH₂) 1.61 (m, 10H, CH₂CH₂COO+OCH₂CH), 1.27 (m, 60H), 0.88 (4 t, 16H,CH₃)

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.13, 174.06, 174.02, 173.53,173.51, 173.32, 132.68, 132.62, 132.38, 132.32, 130.56, 130.44, 130.38,67.73, 67.59, 66.80, 66.64, 42.10, 42.05, 38.76, 38.74, 34.47, 34.43,34.39, 34.01, 33.96, 32.61, 32.57, 32.55, 31.93, 31.89, 31.46, 30.43,30.41, 29.70, 29.65, 29.54, 29.50, 29.37, 29.32, 29.31, 29.25, 29.18,29.17, 29.06, 29.02, 28.93, 28.80, 28.76, 26.88, 25.07, 25.04, 25.01,24.48, 24.45, 23.81, 23.79, 22.99, 22.97, 22.70, 22.68, 14.12, 14.06,11.00, 10.99.

HRMS (ESI): calculated for C₆₀H₁₁₀O₈Na⁺: 981.8093; found: 981.8094.

Example 15 Preparation of (Z)-hexane-1,6-diyldioleate

The synthesis was in accordance with experimental methods of Raghunananet al. (L. Raghunanan, S. Narine ACS Sust. Chem. & Eng. 2016 4 (3),693-700) and Neises et al. (B. Neises, W. Steglich, Angew. Chem. Int.Ed. Engl. 1978, 17, 522-524). Oleic acid (5.01 g, 17.7 mmol),hexane-1,6-diol (804.6 mg, 6.8 mmol), N,N-dimethylaminopyridine (86.7mg, 0.71 mmol) and N,N′-dicyclohexylcarbodiimide (2.84 g, 13.8 mmol)were stirred in dichloromethane at room temperature. After 18 h, thephases were separated and the aqueous phase was extracted three timeswith dichloromethane (1:1 v/v). The combined extracts were dried overmagnesium sulfate and freed of the solvent under reduced pressure. Theproduct was obtained as a yellowish oil.

Yield: 2.79 g, 63%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.34 (4H, m, CH═CH), 4.06 (4H, t,O—CH₂), 2.28 (4H, t, CH₂COO), 2.00 (8H, m, CH═CH—CH₂), 1.63 (8H, m,O—CH₂—CH₂, CH₂—CH₂—COO), 1.21-1.35 (44H, m), 0.88 (6H, t, CH₃).

MS (ESI): m/z=669.6 [M+Na]⁺.

The analytical data correspond to the literature (L. Raghunanan, S.Narine ACS Sust. Chem. & Eng. 2016 4 (3), 693-700).

Example 16 Preparation of a mixture of6-(((E)-9-(hydroxymethyl)octadec-10-enoyl)oxy)hexyl(E)-10-(hydroxymethyl)octadec-8-enoate, hexane-1,6-diyl(10E,10′E)-bis(9-(hydroxymethyl)octadec-10-enoate) and hexane-1,6-diyl(8E,8′E)-bis(10-(hydroxymethyl)octadec-8-enoate)

The synthesis was according to GEM 2. (Z)-Hexane-1,6-diyl dioleate (1.73g, 2.68 mmol) and paraformaldehyde (373 mg, 12.4 mmol) were convertedwith addition of EtAlCl₂ (19 ml, 19 mmol). Workup and columnchromatography (cyclohexane/ethyl acetate 15:1, v/v) gave the desiredproduct as a colorless oil.

Yield: 353 mg, 19%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.51 (m, 2H, CH═CHCH), 5.13 (m, 2H,CH═CHCH), 4.06 (m, 4H, COOCH₂), 3.53 (m, 2H, CH₂OH) 3.32 (m, 2H, CH₂OH),2.29 (t, 4H, CH₂COO), 2.14 (m, 2H, CH═CHCH), 2.02 (m, 4H, CH₂CH═CH),1.63 (m, 8H, CH₂CH₂COO, OCH₂CH), 1.32 (m, 42H), 0.88 (t, 6H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=134.29, 133.92, 131.62, 131.34, 66.13,64.32, 46.10, 34.50, 34.48, 32.83, 32.73, 32.04, 32.01, 31.28, 31.24,29.82, 29.69, 29.64, 29.46, 29.34, 29.29, 29.26, 29.11, 28.91, 28.71,27.25, 27.19, 25.78, 25.13, 25.09, 22.81, 14.26.

HRMS (ESI): calculated for C₄₄H₈₂O₆Na⁺: 729,6004; found: 729,6014.

General Experimental Method 5 (GEMS): Preparation of Higher MolecularWeight Fatty Acid Esters Using the Acid Chlorides

The acid chlorides were purchased commercially or prepared by thefollowing method: thionyl chloride (15 eq.) was slowly added dropwise at0° C. while stirring to the carboxylic acid (1.0 eq.) dissolved intoluene. After heating under reflux for 16 h, the excess thionylchloride and the solvent was removed by means of microdistillation inorder to obtain the acid chloride. This was used immediately.

The fatty acid component with a free alcohol function (1.0 eq.) intoluene was initially charged together with pyridine (1.1 eq.) and,while stirring and cooling with ice, the acid chloride (1.2 eq.) wasadded gradually. The mixture was brought to room temperature within 15min and then heated under reflux for 6-16 h. After phase separation, theaqueous phase was acidified with acetic acid and extracted twice morewith ethyl acetate. The combined extracts were dried over magnesiumsulfate and concentrated to dryness under reduced pressure. Columnchromatography gave the desired products.

Example 17 Preparation of a mixture of 2′-ethylhexyl9-(((12-(hexanoyloxy)octadecanoyl)-oxy)methyl)octadecanoate and2′-ethylhexyl10-(((12-(hexanoyloxy)-octadecanoyl)oxy)methyl)octadecanoate

The synthesis was according to GEM 5. A mixture of 2′-ethylhexyl9-(((12-hydroxyoctadecanoyl)oxy)methyl)octadecanoate and 2′-ethylhexyl10-(((12-hydroxyoctadecanoyl)oxy)methyl)octadecanoate (2.04 g, 2.87mmol) was reacted with pyridine (0.25 ml, 3.16 mmol) and hexanoylchloride (0.5 ml, 3.58 mmol). Workup and column chromatography using aC18-RP column (acetonitrile) gave the desired product as a colorlessoil.

Yield: 8 mg, 2%. 4.86 (s, 1H), 4.01-3.91 (m, 8H), 2.27 (s, 5H),1.76-1.15 (m, 64H), 0.89 (s, 9H).

¹H NMR (500 MHz, CDCl₃): δ [ppm]=4,86 (m, 1H, COOCH), 4.01-3.91 (m, 4H,COOCH₂); 2.27 (m, 6H, CH₂COO); 1.76-1.15 (m, 72H); 0.88 (m, 15H, CH₃).

HRMS (ESI): calculated for C₅₁H₉₈O₆Na⁺: 829.7256; found: 829.7261.

Example 18 Preparation of a mixture6-(((E)-9-((stearoyloxy)methyl)octadec-10-enoyl)oxy)hexyl(E)-10-((stearoyloxy)methyl)octadec-8-enoate, hexane-1,6-diyl(10E,10′E)-bis(9-((stearoyloxy)methyl)octadec-10-enoate) andhexane-1,6-diyl (8E,8′E)-bis(10-((stearoyloxy)methyl)octadec-8-enoate)

The synthesis was according to GEM 5. A mixture of6-(((E)-9-(hydroxymethyl)octadec-10-enoyl)oxy)hexyl(E)-10-(hydroxymethyl)octadec-8-enoate, hexane-1,6-diyl(10E,10′E)-bis(9-(hydroxymethyl)octadec-10-enoate) and hexane-1,6-diyl(8E,8′E)-bis(10-(hydroxymethyl)octadec-8-enoate) (181 mg, 0.26 mmol) wasreacted with pyridine (0.25 μl, 0.28 mmol) and stearyl chloride (95.6mg, 0.31 mmol). Workup and preparative thin-layer chromatography gavethe desired product as a colorless oil.

Yield: 20 mg, 3%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.43 (m, 2H, CH═CH), 5.15 (m, 2H,CH═CH), 4.04 (m, 4H, COOCH₂), 3.94 (t, 4H, COOCH₂—(CH₂)₄—CH₂OOC), 2.28(m, 4H, CH₂COO), 1.98 (m, 4H, CH₂CH₂), 1.61 (m, 10H, CH₂CH₂COO+OCH₂CH),1.45-1.11 (m, 108H), 0.88 (t, 12H, CH₃).

HRMS (ESI): calculated for C₈₀H₁₅₀O₈Na⁺: 1261,1223; found: 1262,1246.

Example 19 Preparation of a mixture of(E)-9-((stearoyloxy)methyl)octadec-10-enoic acid and(E)-10-((stearoyloxy)methyl)octadec-8-enoic acid

The synthesis was according to GEM 5. A mixture ofE-9-(hydroxymethyl)octadec-10-enoic acid andE-10-(hydroxymethyl)octadec-8-enoic acid (428 g, 1.3 mmol) was reactedwith pyridine (0.13 ml, 1.65 mmol) and stearyl chloride (from stearicacid: 467 mg, 1.64 mmol). Workup and filtration through silica gel(cyclohexane:ethyl acetate 15:1 v/v) gave the desired product as acolorless wax.

Yield: 716 mg, 92%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.42 (m, 1H, CH═CH—CH), 5.21 (m, 1H,CH═CH—CH), 3.94 (m, 2H, CH—CH₂—O), 2.34 (m, 2H, CH₂COOH), 2.28 (m, 2H,CH₂—COOCH₂), 2.04-1.93 (m, 2H, CH₂—CH═CH), 1.61 (m, 5H. CH═CH—CH.CH₂—CH₂—COO), 1.25 (s, 47H), 0.88 (t, ³J=6.9 Hz, 6H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=179.15, 179.07, 134.33, 133.88,131.64, 131.30, 66.15, 66.10, 46.06, 34.01, 34.01, 32.82, 32.68, 32.03,32.01, 31.27, 31.21, 29.82, 29.69, 29.68, 29.57, 29.45, 29.37, 29.29,29.28, 29.26, 29.16, 28.99, 28.79, 27.24, 27.15, 27.07, 24.80, 24.75,22.82, 22.81, 14.25.

HRMS (ESI): calculated for C₃₇H₇₀O₄Na⁺: 601.5166; found: 601.5158.

EA: calculated for C₃₇H₇₀O₄ C: 76.76%, H: 12.19%, found: C: 76.71%, H:12.42%.

Example 20 Preparation of a mixture of 2′-ethylhexyl(E)-9-((((E)-9-((stearoyloxy)methyl)octadec-10-enoyl)oxy)methyl)octadec-10-enoate,

2′-ethylhexyl(E)-9-((((E)-9-((stearoyloxy)methyl)octadec-10-enoyl)oxy)methyl)octadec-8-enoate,

2′-ethylhexyl(E)-10-((((E)-9-((stearoyloxy)methyl)octadec-10-enoyl)oxy)methyl)octadec-10-enoateand

2′-ethylhexyl(E)-10-((((E)-9-((stearoyloxy)methyl)octadec-10-enoyl)oxy)methyl)octadec-8-enoate

A mixture of (E)-9-((stearoyloxy)methyl)octadec-10-enoic acid and(E)-10-((stearoyloxy)methyl)octadec-8-enoic acid (271 mg, 0.47 mmol) wasinitially charged together with a mixture of 2′-ethylhexylE-9-(hydroxymethyl)octadec-10-enoate and 2′-ethylhexylE-10-(hydroxymethyl)octadec-8-enoate (188 mg, 0.44 mmol) in toluene, andadmixed with p-toluenesulfonic acid (84 mg, 0.44 mmol) and 4 Å molecularsieve (62 mg, 121.2 mg/mmol). After stirring at 40° C. for 2 h, ice wasadded. After phase separation, the aqueous phase was extracted threetimes with ethyl acetate (1:1 v/v). The combined organic phases werewashed with saturated aqueous sodium hydrogencarbonate solution and thenwith saturated aqueous sodium chloride solution, dried over magnesiumsulfate and concentrated to dryness under reduced pressure.

Column chromatography (cyclohexane: ethyl acetate 20:1 v/v) gave thedesired product as a colorless oil.

Yield: 14 mg, 3%.

¹H NMR (500 MHz, CDCl₃): δ [ppm]=5.42 (m, 2H, CH═CH—CH), 5.21 (m, 2H,CH═CH—CH), 3.98 (m, 2H, CH—CH₂—O-ethylhexyl), 3.96-3.87 (m, 4H,CH—CH₂—O), 2.28(m, 6H, CH₂—COOCH₂), 1.98 (m, 4H, CH₂—CH═CH), 1.68-1.50(m, 8H. CH═CH—CH. CH₂—CH₂—COO), 1.43-1.15 (s, 77H), 0.88 (t, ³J=4.7 Hz,15H, CH₃).

¹³C NMR (125 MHz, CDCl₃): δ [ppm]=174.21, 174.17, 174.05, 174.00,173.96, 132.77, 132.47, 130.76, 130.75, 130.59, 67.74, 67.72, 66.79,42.25, 42.20, 38.90, 34.59, 34.58, 34.55, 32.77, 32.72, 32.70, 32.08,32.04, 31.61, 30.58, 29.86, 29.83, 29.82, 29.80, 29.69, 29.66, 29.52,29.47, 29.46, 29.42, 29.40, 29.35, 29.34, 29.22, 29.21, 29.19, 29.17,29.08, 28.95, 28.91, 27.05, 27.03, 25.20, 25.19, 25.16, 25.14, 23.95,23.14, 22.85, 22.83, 14.27, 14.21, 11.15.

HRMS (ESI): calculated for C₆₄H₁₂₀O₆Na⁺: 1007.8984; found: 1007.8977.

EA: calculated for C₃₇H₇₀O₄ C: 77.99%, H: 12.27%, found: C: 78.17%, H:12.30%.

1. A mixture of at least two ester compounds of the general formula (I)

in which the A radical is selected from the group consisting of CH₂,CH₂CH₂, cis-CH═CH and/or trans-CH═CH, n is 0 or 1 to 20, m is 1 to 20,the R¹ radical is selected from the group consisting of hydrogen,branched or unbranched C₁- to C₆₀-alkyl radicals, branched or unbranchedC₂- to C₆₀-alkenyl radicals, C₇- to C₆₀-arylalkyl radicals, C₁- toC₆₀-heteroarylalkyl radicals, C₆- to C₆₀-aryl radicals, and/orcyclically saturated or unsaturated C₅-to C₆₀-alkyl radicals, wherethese are unsubstituted or mono- or polysubstituted by at least onesubstituent selected from the group of OH, R⁴, R⁵, O-acetyl, the R²radical is selected from the group consisting of H, branched orunbranched C₂- to C₆₀-alkyl radicals, C₂- to C₆₀-heteroalkyl radicals,C₇- to C₆₀-arylalkyl radicals, C₆-to C₆₀-heteroarylalkyl radicals, C₆-to C₆₀-aryl radicals, and/or cyclically saturated or unsaturated C₅-toC₆₀-alkyl radicals, where these are unsubstituted or mono- orpolysubstituted by at least one substituent selected from the group ofOH, O—C(O)—R¹, CH₂OH, CO₂H, CO₂R¹, R⁵, and also branched or unbranchedC₂- to C₆₀-alkenyl radicals or methyl, where this is unsubstituted ormono- or polysubstituted by at least one substituent selected from thegroup of OH, O—C(O)—R¹, CH₂OH, CO₂H, CO₂R¹, R⁵, the R³ radical isselected from the group consisting of branched or unbranched C₁- toC₆₀-alkyl radicals, branched or unbranched C₂- to C₆₀-alkenyl radicals,C₇- to C₆₀-arylalkyl radicals and/or C₆- to C₆₀-heteroarylalkylradicals, where these are unsubstituted or mono- or polysubstituted byat least one substituent selected from the group of OH, CH₂OH, CH₂—R⁴,the R⁴ radical has the following structure (II):

in which the R², R³ and A radicals and the numbers m and n presenttherein are defined as described above, the R⁵ radical has the followingstructure (III):

in which the R¹, R³ and A radicals and the numbers m and n presenttherein are defined as described above.
 2. The mixture of at least twoester compounds as claimed in claim 1, wherein each of the estercompounds in the mixture of at least two ester compounds of the generalformula (I) has the general structure (Ia)

in which n′ and n″ are either 1 and 2 or 2 and 1, m′ is 1 to 5, the R¹radical is selected from the group consisting of hydrogen, branched orunbranched C₁- to C₆₀-alkyl radicals, branched or unbranched C₂- toC₆₀-alkenyl radicals, C₇- to C₆₀-arylalkyl radicals, C₁-toC₆₀-heteroarylalkyl radicals and/or C₆- to C₆₀-aryl radicals, the R²radical is selected from the group consisting of branched or unbranchedC₁- to C₆₀-alkyl radicals, branched or unbranched C₂- to C₆₀-alkenylradicals, C₇- to C₆₀-arylalkyl radicals and/or C₆- toC₆₀-heteroarylalkyl radicals and/or cyclically saturated and orunsaturated C₅-to C₆₀-alkyl radicals, where these are unsubstituted ormono- or polysubstituted by at least one substituent selected from thegroup of OH, CH₂OH.
 3. The mixture of at least two ester compounds asclaimed in claim 1, wherein each of the ester compounds in the mixtureof at least two ester compounds of the general formula (I) has thegeneral structure (Ib)

in which n′ and n″ are either 1 and 2 or 2 and 1, n″' is 0 to 10, m′ is1 to 5, the R² radical is selected from the group consisting of branchedor unbranched C₁- to C₆₀-alkyl radicals, branched or unbranched C₁- toC₆₀-alkenyl radicals, C₇- to C₆₀-arylalkyl radicals and/or C₆-toC₆₀-heteroarylalkyl radicals and/or cyclically saturated and orunsaturated C₅-to C₆₀-alkyl radicals, where these are unsubstituted ormono- or polysubstituted by at least one substituent selected from thegroup of OH, CH₂OH, R⁶ radical is selected from the group consisting ofbranched or unbranched C₁- to C₆₀-alkyl radicals and branched orunbranched C₂- to C₆₀-alkenyl radicals.
 4. The mixture of at least twoester compounds as claimed in claim 1, wherein each of the estercompounds in the mixture of at least two ester compounds of the generalformula (I) has the general structure (Ic)

in which n′ and n″ are either 1 and 2 or 2 and 1, n′″ is 0 to 10, m′ is1 to 5, the R¹ radical is selected from the group consisting ofhydrogen, branched or unbranched C₁ to C₆₀-alkyl radicals, branched orunbranched C₁ to C₆₀-alkenyl s radicals, C₇- to C₆₀-arylalkyl radicals,C₁-to C₆₀-heteroarylalkyl radicals and/or C₆- to C₆₀-aryl radicals, theR⁶ radical is selected from the group consisting of branched orunbranched C₁- to C₆₀-alkyl radicals and branched or unbranched C₂- toC₆₀-alkenyl radicals.
 5. The mixture of at least two ester compounds asclaimed in claim 1, wherein two of the at least two ester compounds ineach case are regioisomers of one another.
 6. The mixture of least twoester compounds as claimed in claim 2, wherein two of the at least twoester compounds in each case are regioisomers of one another.
 7. Themixture of least two ester compounds as claimed in claim 3, wherein twoof the at least two ester compounds in each case are regioisomers of oneanother.
 8. The mixture of least two ester compounds as claimed in claim4, wherein two of the at least two ester compounds in each case areregioisomers of one another.
 9. The mixture of least two ester compoundsas claimed in claim 1, further comprising at least one further ester nothaving the general formula (I).
 10. The mixture of least two estercompounds as claimed in claim 9, wherein the at least one further esteris selected from the group consisting of trimethylolpropane andpentaerythritol esters, TMP complex esters in fully or partly esterifiedform with saturated and/or mono- or polyunsaturated carboxylic acids ofchain length C6-C36, where these may be linear or branched, complexesters of dimer acids, dimer acid esters, ethylhexyl dimerate, aliphaticcarboxylic, dicarboxylic esters, phosphate esters, trimellitic andpyromellitic esters, and natural glyceride ester.